Dual redundancy system for electronic detonators

ABSTRACT

A detonator assembly ( 10 ) comprising a housing ( 12 ) disclosed and claimed. The assembly comprises an main circuit ( 11 ) comprising an electrically operable fuse ( 16 ) located in the housing. The assembly further comprises at least a first redundancy circuit ( 13 ) wherein at least one element of the main circuit is duplicated ( 18  for  16 ) also located in the housing. The invention also includes within its scope an initiation system ( 42 ) comprising at least one level of redundancy which may be in one or more or all of a blast controller ( 24 ), a harness ( 40 ) and detonator assemblies  10.1  to  10.   n  forming part of the system.

TECHNICAL FIELD

[0001] THIS invention relates to detonators, more particularlyelectrical and electronic detonators, initiation systems comprising suchdetonators and to a method of manufacturing the detonator and/or thesystem.

BACKGROUND ART

[0002] Detonator assemblies comprising an electrical or an electronicdetonator connected via lead wires to a harness are known in the art. Inuse, a plurality of such assemblies are connected via the harness to ablast controller and located in respective blast holes of a blast site.The blast controller is used to control the detonators and to cause themto detonate in a particular sequence and pattern, to cause a desiredmulti-shot blast pattern.

[0003] Due to certain reliability problems with the detonatorassemblies, it is the practice in some countries to place in each blasthole a first detonator assembly as well as a second, parallel or back-updetonator assembly. It will be appreciated that the provision andconnecting of a separate, parallel back-up detonator assembly not onlytake up unnecessary time, but are cumbersome and errors may occur in theconnection of the back-up assembly.

OBJECT OF THE INVENTION

[0004] Accordingly, it is an object of the present invention to providea detonator assembly, a initiation system and a method of manufacturingthe detonator assembly and system with which the applicant believes theaforementioned disadvantages may at least be alleviated.

SUMMARY OF THE INVENTION

[0005] According to the invention there is provided a detonatorcomprising a housing; a main circuit comprising an electrically operablefuse located in the housing; and at least a first redundancy circuitwherein at least one element of the main circuit is duplicated, alsolocated in the housing.

[0006] The detonator may be an electric detonator, alternatively anelectronic detonator.

[0007] The main circuit may comprise the fuse, a charge storage deviceand a controller. The charge storage device may be a capacitor and thecontroller may be micro-processor based and may further compriseassociated memory circuitry, delay time determining circuitry and datacommunications circuitry.

[0008] The redundancy circuit may be a full redundancy circuitcomprising a fuse, a charge storage device and a local controller. Inother embodiments, further levels of full or partial redundancy may beprovided.

[0009] The main circuit and redundancy circuit may be provided on asingle printed circuit board. The main circuit and redundancy circuitmay be provided on one face of the board, in other embodiments they maybe provided on both faces and in yet other embodiments the main circuitmay be provided on the one face and the redundancy circuit may beprovided on the other face. In yet other embodiments the main circuitmay be provided on a first printed circuit board and the redundancycircuit may be provided on a second printed circuit board, both printedcircuit boards being located in the housing.

[0010] Further included within the scope of the present invention is adetonator assembly comprising a detonator as hereinbefore defined; aconnector and a connection cable extending between the connector and thedetonator.

[0011] The connector and/or the connection cable may also comprise atleast a first level of redundancy. For example, the connection cable maycomprise a main conductor arrangement and a first redundancy conductorarrangement extending between the detonator and the connector.Similarly, the connector may comprise a main set of contacts and a firstset of redundancy contacts both connected to the first conductorarrangement, or to respective ones of the conductor arrangements, or toboth conductor arrangements.

[0012] Still further included within the scope of the present inventionis a blast controller comprising a housing: a main circuit located inthe housing and connectable to an output for communicating with andcontrolling detonators connected to the output; and a first redundancycircuit wherein at least one element of the main circuit is duplicated,also located in the housing and connectable to the output.

[0013] The first redundancy circuit may comprise a full duplication ofall the elements of the main circuit, so that it is a full redundancycircuit. The main circuit and the first redundancy circuit may eachcomprise circuit status monitor means connected to a central controller,the central controller being operative in response to signals from thecircuit status monitor means, to connect either the main circuit or thefirst redundancy circuit to the output of the blast controller.

[0014] Yet further included within the scope of the present invention isa initiation system comprising a blast controller as hereinbeforedefined; and a plurality of detonator assemblies also as hereinbeforedefined, the assemblies being connected to a harness connected to theoutput of the blast controller.

[0015] The harness may also comprise at least a first level ofredundancy. The invention also includes within its scope a harnesshaving at least a first level of redundancy.

[0016] Also included within the scope of the invention is a method ofproducing a component (such as a detonator, blast controller etc) of anelectrically controllable detonator initiation system, the methodcomprising the steps of

[0017] providing a housing for the component;

[0018] providing a main circuit of the component in the housing; and

[0019] providing a first redundancy circuit in the housing, the firstredundancy circuit comprising at least one element of the main circuitduplicated in the redundancy circuit.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

[0020] The invention will now further be described, by way of exampleonly, with reference to the accompanying diagrams wherein:

[0021]FIG. 1 is a block diagram of an electronic detonator assemblyaccording to the invention; and

[0022]FIG. 2 is a block diagram of an initiation system including ablast controller, both according to the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0023] A detonator assembly according to the invention is generallydesignated by the reference numeral 10 in FIG. 1.

[0024] The detonator assembly comprises a housing 12 for a printedcircuit (PC) board 14. On the PC board there is provided a main circuit11 comprising a detonator bridge or fuse 16. A first redundancy circuit13 comprising a second bridge 18 is also provided on the board. Thebridge 16 and bridge 18 may be provided on the same face of the PCboard, alternatively on opposite faces thereof. Similarly, the circuit11 and circuit 13 may be provided on the same face of the PC board,alternatively on opposite faces thereof.

[0025] The main circuit 11 comprises a charge storage capacitor 20. Thecapacitor 20 and bridge 16 are charged and controlled respectively inknown manner by a controller embodied in a main application specificintegrated circuit (ASIC) 23. The ASIC 23 comprises electronic circuitryincluding a microprocessor based controller (not shown), associatedmemory arrangements (not shown), digital delay time determining means(not shown) and digital circuitry (also not shown) enabling andfacilitating digital data communications between the controller and anexternal device, such as a blast controller 24, shown in FIG. 2.

[0026] The capacitor 22 and bridge 18 of redundancy circuitry 13 arecharged and controlled respectively by a similar and first redundancyASIC 26.

[0027] Input resistors 28 and 30 for ASIC 23 and redundancy ASIC 26respectively are also provided on the PC board 14.

[0028] In other embodiments the redundancy circuit 13 comprising bridge18, capacitor 22, ASIC 26 and input resistors 30 may be provided on asecond and separate PC board (not shown), but which is located in thesame housing 12.

[0029] The input resistors 28 and 30 are connected via a main and firstbackup lead in the form of twisted pairs 32 and 34 to a connector 36. Inother embodiments protection arrangements (not shown) may also beprovided between the ASIC's and conductors 32 and 34.

[0030] The connector 36 comprises a main set of contacts 36.1 fortwisted pair 32 and a first set of redundancy contacts 36.2 for twistedpair 34.

[0031] The blast controller 24 is shown in FIG. 2. In use, it ispositioned remote from the blast face 37 and blast holes 38.1 to 38.n.

[0032] In each hole, a detonator assembly 10 as hereinbefore describedand comprising at least one level of partial or full redundancycircuitry as hereinbefore described is located in known manner. In FIG.2, detonator assembly 10.1 for first hole 38.1 and detonator assembly10.n for the nth hole 38.n are shown.

[0033] The detonator arrangements 10.1 to 10.n are connected to theblast controller 24 by at least a first level of redundancy harness 40comprising cables 40.1 and 40.2 and respective contacts 36.1 and 36.2 ashereinbefore described.

[0034] According to the invention, the blast controller 24 may also beprovided with any desired level of redundancy to pitch the reliabilityof the initiation system 42 at a desired level. In FIG. 2, a blastcontroller 24 with a first level of redundancy is shown, merely as anexample.

[0035] The blast controller 24 comprises a battery 44, batterymanagement means 46, a main power supply unit 48 for the blastcontroller 24 and a back-up power supply unit 50 for the blastcontroller 24.

[0036] The blast controller 24 further comprises a micro-processor basedcontroller 52 operable to control a main branch 54 and a first back-upor redundancy branch 56.

[0037] The main branch includes a modulator/demodulator 58 for datasignals (preferably digital) to be transmitted to the detonatorassemblies 10.1 to 10.n and to be received therefrom. A power amplifier60 amplifies the relevant signals. A branch status monitor circuit 62connected to the processor 52 monitors the status of the main branch 54.The main branch 54 and back-up branch are connected to a switchingcircuit 64, for example in the form of a double pole change over relay,to connect, under control of the controller 52 and depending on thestatus of the branches, the one branch 54 or the other branch 56 viaoutput 72 to the harness 40.

[0038] The other branch 56 is similar to the main branch 54 and afeed-back loop 66 is provided between branch status monitor circuits 62,68 and the controller 52. The controller 52 controls the switchingcircuit 64 via line 70 in response to status signals received fromstatus monitor circuits 62 and 68. Should there be a fault or failure inbranch 54, the controller automatically causes switching circuit 64 toswitch back-up branch 56 to be connected via the output to harness 40,to communicate with and control the detonator assemblies 10.1 to 10.n.

[0039] The invention provides a single detonator assembly 10 which has afirst level or higher of full or partial redundancy. Furthermore, theblast controller 24 has parallel branches 54 and 56 one of which mayautomatically be elected by the controller, to provide back-up and henceimproved reliability.

[0040] The invention also extends to a method of manufacturing detonatorassemblies 10 and a blast controller 24 having at least a first level offull or partial redundancy as hereinbefore described. This means that atleast essential parts of a main circuit is duplicated in a parallelback-up or redundancy circuit.

[0041] It will be appreciated that there are many variations in detailon the detonator assembly, harness, initiation system, blast controllerand method of manufacture as herein described without departing from thescope and spirit of the appended claims.

1. A detonator comprising a housing; a main circuit comprising anelectrically operable fuse located in the housing; and at least a firstredundancy circuit wherein at least one element of the main circuit isduplicated, also located in the housing.
 2. A detonator as claimed inclaim 1 wherein the detonator is an electronic detonator.
 3. A detonatoras claimed in claim 1 or claim 2 wherein the main circuit comprises acharge storage device and a local controller.
 4. A detonator as claimedin claim 3 wherein the charge storage device comprises a capacitor andthe controller is microprocessor based and further comprises associatedmemory circuitry, delay time determining circuitry and datacommunications circuitry.
 5. A detonator as claimed in claim 3 or claim4 wherein the redundancy circuit is a full redundancy circuit comprisinga fuse, a charge storage device and a controller.
 6. A detonatorassembly comprising a detonator as claimed in any one of claims 1 to 5,a connector and a connection cable extending between the connector andthe detonator.
 7. A detonator assembly as claimed in claim 6 wherein theconnection cable comprises a main conductor arrangement and a firstredundancy conductor arrangement.
 8. A detonator assembly as claimed inclaim 7 wherein the connector comprises a main set of contacts connectedto the main conductor arrangement and a first set of redundancy contactsconnected to the first redundancy conductor arrangement.
 9. A detonatorarrangement as claimed in claim 8 wherein the main and first redundancyconductor arrangements comprise first and second twisted pairsrespectively, wherein the first twisted pair is connected at one endthereof to the main set of contacts and at another end thereof to themain circuit and the first redundancy circuit, and wherein the secondtwisted pair is connected at one end thereof to the first set ofredundancy contacts and at another end thereof to the main circuit andthe first redundancy circuit.
 10. A blast controller comprising ahousing: a main circuit located in the housing and connectable to anoutput for communicating with and controlling detonators connected tothe output; and a first redundancy circuit wherein at least one elementof the main circuit is duplicated, also located in the housing andconnectable to the output.
 11. A blast controller as claimed in claim 10wherein the main circuit and the first redundancy circuit each comprisescircuit status monitor means connected to a central controller, thecentral controller being operative in response to signals from thecircuit status monitor means, to connect either the main circuit or thefirst redundancy circuit to the output of the blast controller.
 12. Aninitiation system comprising a blast controller as defined in any ofclaims 10 and 11; and a plurality of detonator assemblies as claimed inany one of claims 6 to 9, the assemblies being connected to a harnessconnected to the output of the blast controller.
 13. A harnesscomprising a main path for electronic signals and a first redundancypath for such signals.
 14. A detonator initiation system comprising ablast controller and at least one detonator connectable to the blastcontroller, at least one of the blast controller and the detonatorcomprising a main circuit located in a housing therefor and a firstredundancy circuit wherein at least one element of the main circuit isduplicated and located in the housing.
 15. A system as claimed in claim14 wherein the detonator is connected to the blast controller by aharness and wherein the harness comprises a main path for signalsbetween the blast controller and the detonator and a first redundancypath for the signals.
 16. A method of producing a component of anelectrically controllable detonator initiation system, the methodincluding the steps of: providing a housing for the component; providinga main circuit of the component in the housing; and providing a firstredundancy circuit in the housing, the first redundancy circuitcomprising at least one element of the main circuit duplicated in theredundancy circuit.